Genetic and environmental contributions to the expression of hand preferences were assessed in a sample of chimpanzees. Furthermore, the possible consequences and neuroanatomical correlates of hand preference were examined in the chimpanzees. The findings from this year indicate a) that hand preferences are heritable in chimpanzees, b) gestural communication is primarily exhibited by the right-hand. Additionally, the chimpanzees exhibit neuroanatomical asymmetries that are human-like in pattern. Finally, preliminary analyses suggest that left- and right-handed chimpanzees differ with respect to immunological functioning. Taken together, the results of this study further our understanding of the role of laterality as a marker of reduced fitness in humans.